Earth moving, construction and mining equipment and the like work are often used in rough, off-road terrain. These machines often employ an endless drive with track shoes that is better able to propel the machines in such environments over obstacles and uneven terrain, etc. The track chains, which include shoes, are held together by a series of interconnected track links, pins and bushings that are supported on the drive sprocket, idler and support rollers of the machine. As can be imagined, a device is typically provided that allows the track chain to be routed about the drive sprocket, idler and support rollers before the free ends of the chain are joined together. This device is called a “master link”.
Also, depending on the weight of the machine, the size of the chain, the environment in which the machine operates, and other factors, the chains and/or track shoes may wear or be damaged and may require periodic inspection, servicing, repair, and/or replacement. Hence, a master link may also be provided in the chain to allow disassembly of the chain (i.e., separation of two ends of the chain).
As can be imagined, it is desirable for master track links to have at least three traits. First, it is desirable that the master track links be reliable or durable. That is to say, the master track link should not be prone to unintentional disassembly when a track chain is in use. If this happens, the track chain assembly may fall off the undercarriage of the machine, leading to unwanted downtime and maintenance of the machine to get the machine up and running again. Second, it is desirable that the master track link be able to be easily serviceable. That is to say, it should not be time consuming to detach the master track link so that maintenance as described above can be performed. Third, it is desirable to be able to cost effectively manufacture the master track link.
Some master track link designs in current use a pin that is press fit into the master track link while others use a pin that is slip fit and held into place using a cotter pin. The press fit provides a low cost, robust design in terms of reliability or durability but is not easily serviced. On the other hand, the slip fit pin is higher cost but provides a robust design in terms of serviceability, however, it is less desirable in terms of durability or reliability. If the cotter pin falls out, the master track link will often fall off the pin.
Accordingly, a need exists for a method and apparatus related to a master track link that can provide a better combination of serviceability, durability or reliability and cost.
One prior master track link using a clamping method to hold onto pins is disclosed in U.S. Pat. No. 7,877,977 to Johannsen et al. The '977 patent suggests providing a clamping master track link that is configured to clamp on bushing/pin combinations on both ends of the master track link (see FIGS. 4 and 5 of the '977 patent). Furthermore, it discloses a straight link where the holes configured to clamp on the bushing/pin combinations are in the same plane. However, this is incompatible with many track chain assembly designs already in the field. Also, this master track link design uses three small gaps between the struts, which require expensive machines such as grinding or wire EDM to manufacture the track link. Therefore, a master track link that is less costly, more durable or reliable, and more serviceable and that can be retrofitted with track chain assemblies already in the field is still warranted.